previous
描述 (Description)
它确定已更改属性的先前值。
语法 (Syntax)
model.previous(attribute)
参数 (Parameters)
attribute - 它表示模型的属性。
例子 (Example)
<!DOCTYPE html>
<html>
<head>
<title>Model Example</title>
<script src = "https://code.jquery.com/jquery-2.1.3.min.js"
type = "text/javascript"></script>
<script src = "https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.2/underscore-min.js"
type = "text/javascript"></script>
<script src = "https://cdnjs.cloudflare.com/ajax/libs/backbone.js/1.1.2/backbone-min.js"
type = "text/javascript"></script>
</head>
<body>
<script type = "text/javascript">
var model = new Backbone.Model ({
id:01,
player:'Sachin'
});
model.set('id', '02');
document.write(
"Value of id after set: ", JSON.stringify(model.changedAttributes()));
document.write("<br>");
document.write("The previous value of id is: ", model.previous('id'));
</script>
</body>
</html>
输出 (Output)
让我们执行以下步骤来查看上述代码的工作原理 -
将上述代码保存在previous.htm文件中。
在浏览器中打开此HTML文件。
